Electrical contact assembly



Aug. 25, 1953 B. voLGovsKoY ELECTRICAL CONTACT ASSEMBLY 2 SheetsShee`t l Filed Dec. `2l, 1951 INVENTO da' Boms VoLGovsKoY www, j' y 22% 2 Sheets-Sheet l2,

` Filed Deo. 21, 1951 Patented Aug. 25, 1953 ELECTRICAL CONTACT ASSEMBLY Boris Volgovskoy, Mount Lebanon Township, Allegheny County, Pa., assignor, by mesne assignments, to McGraw Electric Company, a

corporation of Delaware Application December 21, 1951, serial No. 262,700

3 Claims.

` This invention relates to a new electrical contact assembly for current-interrupting service. More particularly, it pertains to a novel contact construction of the knife-edge and laterally separable blade type in which there is material localizing of any arcing and pitting in service and in which any part affected is readily adjustable and/or replaceable as occasion demands.

One form of electrical contact assembly heretofore used had laterally separable contacts which in use, regardless of how quickly the contacts were opened or closed, had a tendency to arc and pit not only at the outer ends but also intermediate the ends of the separable contacts. The supporting bar for the separable contacts was similarly affected. On the other hand, without such a supporting bar, there would have been no practicable way to mount the separable contacts and hold them in proper position regardless of whether the switch were opened or closed. In

many such constructions, also, the assembly was so integrated that the removal of even a part thereof was a relatively diflicult task and sometimes had the result that the pitting of only a portion of the assembly might cause the entire assembly to have to be discarded. Further, in other cases, the construction was such that the arcing and pitting described adversely affected `not a removable portion only of the entire assembly but so much of it that, again, the entire unit might have to be wholly discarded.

In the new combination of this invention, the foregoing difiiculties have been overcome. Regardless of the magnitude of the current flow to be started or interrupted by the new contact assembly disclosed herein, arcing and pitting are materially localized and confined to the part especially designed for such phenomena. At the same time, that part is affected only in the prescribed portion thereof adapted for it and there is no arcing or pitting intermediate the ends of the laterally separable contacts. In this new construction provision is made for a plurality of separable contacts in a tiered arrangement and `novelly hinged and connected for the ready disassembly of any part of the entire assembly affected by any arcing and/or pitting. Means are also provided in this new case for confining any arcing and pitting which does occur in the use of the new switch mechanism to generally not more than one of the contacts in the tiers. As a consequence, the new construction is relatively trouble-free and inexpensive to maintain and will provide longer life and more eiective service than prior devices of the same general type.

(Cl. ZOO- 162) Other objects and advantages will be apparent from the following description and from the drawings, which are illustrative only, in which:

Figure 1 is a view in elevation, partly in section, of one embodiment of the new construction of this invention;

Figure 2 is a view taken along line II-II of Figure 1;

Figure 3 is a view similar to the view shown in Figure 2 with, however, themovable contact out of engagement with the elongated contacts thereby placing the new assembly in open circuit condition;

Figure 4 is a view in elevation of the new assembly with the circuit in circuit open condition, the elongated tier contacts being in position as shown in Figure 3;

Figure 5 is a view in elevation of the new as` sembly shown in Figure 4 with the movable contact in the intermediate position of initial eircuit closing or nal circuit opening position relative to the elongated tier contacts; and

Figure 6 shows the new assembly in circuit closed condition corresponding to the position shown in part in Figure l.

Referring to the drawings, a new assembly I0 made in accordance with one embodiment of this invention may be used, for example, in a transformer circuit switch for interrupting electric current flow in the course of tap-changing under load. A panel II of suitable insulating material and suicient structural strength may be used for the mounting of the relatively fixed elongated tier contacts I2 and their cooperating relatively movable knife-edge contact I3. Elongated contacts I2 are in a tiered arrangement as shown in Figures 1 and 4 to 6. Each tier has one contact I2 therein which comprises elongated opposedsides I4, the outer ends I5 of which may be outwardly ilared and may be provided with arc-resisting electrically conductive tips I 6. The sides I4 may be constructed of a highly electrically conductive metal or metal alloy.` The inner ends I'l of the respective sides I4 in each Contact I2 are outwardly bent so as to partially surround a hinge pin I 8 for hinging action therewith.` I

A conductive contact block I9 is rigidly bolted to panel I I by bolts 20, a lock washer 2| and a positioning washer 22 being also provided. In horizontal section block I9 is generally Tshaped, the bent ends Il fitting into the respective corners ISa between the head of the T and the stem 23 to retain the respective ends Il of each side of each Contact I2 in hinging relation rela` E tive to the respective pins I8 on the two sides of the stem 23 integral with block I9. A pad 24 may be bonded to the insides of the respective sides I4 adjacent ends II and may be made of a high conductivity silver alloy for rubbing engagement against a collector plate 25 of similar metal bonded to block I3 along each side ofstem 23. Thus, regardless of whether a contact I2 is in its opened or separated position as shown in Figure 2, or, in its closed position as shown in Figure 3, the pads 24 bear againstY the respective collector plates 25. Each collectorplate 25 may extend the entire heightof block `Ij9 thereby making engagement with all'of the pads 24 of all the contacts I2 in the respective tiers.r The pads 24 may be aflixed to the respective sides VIll by soldering or other surface-tosurface bond and z similar surface-to-surface contact may be pro-V` vided between the respective plates 25 and block A pair of cap plates 23 extend in the same general direction as elongated contacts I2 and are secured to the assembly by bolts 21 engaging alignedand correspondingly tapped holes in block I9. The opposed faces 28 of cap plates 26 have countersunk openings 2,9 therein on each side oi stem 23 to serve as aligned sockets on each sideof stem 23 for the respective ends of each hinge pin I8. Vertical spacing of the contacts I2 'along the height of the hinged pin I8 is Vobtained by means of washers 33 interposed between sides I4 of adjoining contacts I2 and between cap plates 23 and contacts I2 as the casemaybe. e

The 4outer ends of the respective cap plates 26 are drilled for the passage of a bolt 3I therethrough, a nut 32 and lock washer 33 being used to hold bolt 3I tightlyin place. A tubular sleeve 34 ofi Bakelite or fiber electrical insulation fits over 'the shank of bolt v3I between the opposed faces of plates 26. By making sleeve 34 to relatively. close dimensions, and tightening up on nut 32, Vtheouter ends 25a of the plates 26 can be made very rigid in the courseof assembling the new device.

Intermediate the ends of each contact I2, the sides `Ill thereof are Vprovided with openings 35 therethrough, the said openings being in alignment. Through'those openings in each tier, a bolt 3E is passedto serve inconjunction with a nut 31 as a retainer for the springs 38. The

I4 in each of the tiers extends outwardly in a rm manner so that no side of any contact I2 will droop. Instead, all contacts I2 will remain parallel, as shown in the drawings,l throughout their periodv of service. In their position the inner sides of vsides I4 of each contact I2 bear against sleeve 34, the exterior diameter of which is selected to maintain a gap 4l) between the respective tips I6 ofeach pair of contacts I2 when in the position shown in Figure 3. The gap 40 liesone-half on each side of a median plane passing through the axis of bolt 3| and midway between the sides I4 of the respective tiers I2. A bus-bar 4I is welded to block I9 and passes through an opening 42 in panel II for connection with whatever circuit the new contact assembly 'of this invention may be used.

The relatively movable contact I3 is in the form of a knife blade of a lconductive metal and is springs 3B are'positioned between the outside A of the respective sides I4 and the head 39 of the bolt on the one hand and nut 31 on the other hand. In general, the springs 38 will be V'of equal strength to exert similar force on` the respective sides I4 of each contact I2. In addition, a lock washer 31a or other means such asa cotter pin may be used to'prevent any change in the distance between head 39 and nut 3l. By the same token, the force exerted by the respective springs 38'on each bolt `3B can be adjusted as required by changing the distance between the head v39 and the nut 31 in assembling the'n'ewjdevice. Sincethe diameter of the springs 38 is 'greater than that of the holes'35, the springs 38 'actito push the sides I4 of each Contact I2 in veach tier into the closed or unseparated position shown in Figure 3.

The height of the sides I4 at each end I'I in each contact I2, the proportions ofthe washers 30, 'the relative fit of inner ends I1 around the hingek pins I8 and, the fit of the aforesaid cor nersIS'a in holding ends II in hinging relation relativeto the pins I8, are such that each side provided with a tapered lnose 43 which may also be made of an arcfresisting refractory conductive material welded or otherwise bonded'to the back of Aknife edge I3. Contact I3 Ais bolted 'by a bolt |30. to a metal arm* lllV which 'swings in an arc about `a pivot bolt 45. `Contact I3 readily removable and is provided Awith ajrea'rf wardly extending tenon I3b which rits in Aa slot between lugs 44d integral Ywith arm 44. The tenen I 3b and lugs 44a are drilled through an Valignment for `receipt of the 'bolt and nut assemblyl I3a which Vholds contact I3 'rigidly 'in place on arm fifi 'so vas to `form a rigid integral part thereof during movement and service. Y

Pivot bolt 45 passes through drilled openings inthe sides of the lowerclevisedjend of yarm`44 and may be mounted in any `suitable manner. In the assembly I9, pivot bolt 45V passes through an aligned drilled opening through the outer end of a V-shaped bracket 46 lor metal having'its respective bases 4l rigidly (held in place by* bolts 4?. extending throughpanel I`I and an insulating mounting `block 49 into correspondingly drilled and tappedopenings in bases `4l.1 The-bracket fits between the sides of the drilledand 'hushed lower clevis endof arm 44 through whichbolt'45 valso passes. f Y

Outwardly of the sides of ar'rndliarejapairof metal conductor bars extending between'pivot 45 and a lower conductive block 5I. Bolts`52 fasten the ends nofbars 53 adjacent block 5I "to the respectivesides thereof. `'Albus-*bar 53 is welded to block "5I and extends Athrough lregistering openings in insulation members V 49 and *II tobe connectedtojan'other part of the aforesaidjcirrcuit inconnectionrwith'which the-new devicemay 'beuse'dso as "to permit electric current to iiow through said circuit whenl the'parts of the new deviceare in the position shown in Figure 6`and to interrupt the flow of such current when the parts are in position shown in Figure 4. j A bolt and nut' assembly 54 connects rthebars 50 'on opposite sides of arm-44`to assist in holding the relative members surrounding pivot'b'olt45 in position withoutv undue pla-y. lSuitable washers may be placed onV pivot 45 between the sides ofthe bracket member 45 and the inside of thefclvis-of arm `44. Belleville Washers 55 mayj'beemployed between the head and nut respectively-of thepivot vbolt and nut fsubassembly V45 fto Vprovide locking andV good Contact ,during the arcuate `swingingt'f arm 44 and contact I3 in the aforesaidrrnedian plane in the course of serviceas *shown inf-the positions illustrated in Figures 4 toVV 6.

' The-lowerfen'd of V larm 44 is'A also providedwith an extensio`n -56 whichtscbtween thesidesof a clevis 51 to which it ishingedly connected by a pin 58; Clevis 5l isbolted to a connectingmember 59 which may be of suitable laminated Bakelite or insulated ber material. The lower end of connecting member 59may be bolted in turn to a bracket BIJ- pivotally connected to a bell crank 6I. Bell crank 6I may beA arcuately, rotated in a conventional bearing block 62 fastened to a structural frame member 63, forming a part, for` example, of the transformer tap-changer or `other structure with which the new device is to be used. The ends 64 of crank 6I may be connected to a conventional toggle mechanism or other device for moving arm 44 through an arc of the magnitude depicted by the extreme positions shown in Figures 4 and 6 in response to the demands of the circuit in which the new device is connected to make and break the circuit respectively by the engagement and disengagement of contacts I2 and I3.

The acute angle dened by and between the surfaces 65 of the nose 43 corresponds generally to the angle formed by the provisional engagement surfaces 66 of tips I6 when in the unseparated position as shown in Figure 3. Further, in the embodiment shown, a line joining either the tips I 6 or the surfaces 6B of the contacts I2 in the respective tiers, is a vertical line. On the other hand, there is no coincidence between that vertical line and the line of direction in which nose 43 extends in the median plane midway between the surfaces 65 and parallel thereto. Hence, in making initial engagement as in the case of contact I3 being swung from a position as shown in Figure 4 to a position as shown in Figure 5, the uppermost contact I2 would have its tips slidably engaged first by the uppermost part of nose 43. Further movement of contact I3 into full engagement position, fully closing the circuit through the bus-bars 4I and 53, will successively provide contact with each of the other contacts I2 in turn moving from top to bottom thereof as shown in Figures 5 and 6. In such full engagement, the engagement surfaces 66a bear against contact I3.

Conversely, in interrupting the current flowing through the new assembly I0, the lowermost contact I 2 will return to the position shown in Figure 3 to be followed in turn by the successive disengagement of the contacts I2 immediately above from any bearing against contact I3, while contact I3 is returning from a position as shown in Figure 6 to a position as shown in Figure 4. In this way, whatever arcing occurs will substantially be entirely at the tips I6 of the uppermost contact I2 and at the uppermost part of nose 43. As and when those tips I6 as a consequence might Warrant resurfacing or replacement, the upper cap plate 26 may readily be removed enabling the sides I4 of uppermost contact I2 to be lifted olf the hinge pins I8 for such resurfacing or replacement by another contact I2 without affecting the contacts I2 on the lower tiers. On the other hand, the ends I7 of sides I4 may be made short enough while still providing suitable hinging contact to enable any side I4 of any tier I2 to be withdrawn from the assembly by first removing the parts 36-31-38 engaging the side I4 to be removed and then swinging that side I4 outwardly until the end Il thereof can be slid out in the space between its hinge pin I8 and its collector plate 25 and in a direction toward and normal to the axis of bolt 3 I.

Moreover, even if the arcing that does occur in connection with the uppermost tier I2 should eventually offer undue: resistance to the1f10w of current through the uppermost contact I2 when the switch is closed, the lower tiers I2 willreadily provide `a conductive path for any resulting augmented flow of electric current therethrough. Thereby, the new electrical contact assembly of this invention may be continued in service with assurance that at alltimes there will be effective load carryingcapacity in the new assembly and` that there ean be no intermediate arcing along any of the sides I4 because of the insulating nature of the sleeve 34 at the time of relative movement of the sides I4 in any contact I2 due to the swinging of movable contact I3 in the median plane. At the same time whenever any contact part of the relatively fixed contacts I2 or the movable contact I3 does require redressing or replacement, its removal and/or replacement may readily be performed. If desired, conventional arc chutes may be used to enclose the fixed contact assembly comprising the contacts I2, suitable openings being provided in the chute for the engagement and disengagement of contact I3 relative to the contacts I 2.

The new construction of this invention may be variously embodied without departing from the spirit of the invention as defined by the appended claims.

I claim:

1. In an electrical contact assembly, in combination, a contact having a pair of generally elongated oppositely disposed sides, a hinge pin adjacent one end of said sides, at least one of said sides having its adjacent end fitting around said hinge pin to hinge said side, a non-conductive stop positioned between said sides intermediate the respective ends thereof including a cross bolt and an insulating sleeve surrounding said bolt, means for relatively pressing said sides toward each other and against said stop when said assembly is in open circuit condition, and a contact movable relative to said first-mentioned contact into and out of engagement with and between the other ends of said first mentioned contact to make and break an electrical circuit and an arc resisting electrically conductive tip at the` outer end of each contact side member.

2. An electrical contact assembly, in combination, a plurality of generally elongated contacts Y in tiered arrangement, each of said contacts having a pair of oppositely disposed spaced sides. means for hinging all of said contacts adjacent a corresponding end of each thereof, means for relatively pressing said sides toward each other, an insulating stop positioned between the respective sides of each contact intermediate the ends thereof including a cross bolt and an insulating sleeve surrounding said bolt, and a contact movable relative to said first-mentioned contacts generally in a median plane between the respective sides of said first-mentioned contacts to make and break an electrical circuit and an arc resisting electrically conductive tip at the outer end of each contact side member.

3. In an electric current making-and-breaking contact assembly, in combination, a plurality of generally elongated parallel contacts, each contact comprising a pair of separable sides, a T-shaped contact block, the stem of said block extending between the inner ends of said sides respectively of said contacts, cap plates in opposed relation fastened t0 the ends of said block, hinge pins extending between said cap plates adjacent said stem, a collector plate bonded to said block along each side of the stem thereof, the

inner vends of said 'respective sides of leach of said contacts partially surrounding the adjacent hinge pin 'and extending .between it vand the 'corner of said-contact block adjacent thereto, said sides being in `corYti-nuous engagement 'with said `collector 5 'sad'stop 'having adiamete'r 'suicent to provide 10 `a 'gap between 4the outer ends `of said vsides 'of said contacts when said sides are pressed against said stop by said means.

' BORIS VOLGO-VSKOY.

References Cited in the le of this patent UNITED STATES PATENTS Name Date Bauerschmdt Oct. 23, 1934 Number 

